Question

Given below are the entries in a savings Bank A/c pass book.

Calculate the interest for six months from February to July at 6% p.a.

Answer 1

Hint: At first fill up the blanks with their respective amounts and then apply formula,
Simple interest =$\dfrac{Principle\times Rate\times Time}{100}$

Complete step-by-step answer:
In the give table we will first complete the table by filling blanks;

By default Rs. 8500 was given. After withdrawing Rs4000 on Feb 18, Rs. 4500 is left (that is 8500-4000=4500).
On April 12, Rs.2230 was deposited to make the balance of Rs. 6730 (that is 4500+2230=6730).
On June 15, again Rs. 5000 was withdrawn to make the balance Rs.1730 (that is, 6730-5000=1730).
Finally on July 8, Rs.6000 was deposited to make Rs. 7730 (that is, 1730+6000=7730) which is the available balance.
Now we will check the balance between 10^th day and the last day of respective months in the above table. Be careful, no transaction is done in the month of March so the balance at the end of March will be the same as that of February. Same will be the case in the month of May.
At the end of February, the minimum balance = Rs. 4500
As no transaction is done in the month of March so the balance at the end of March will be the same as that of February. So, the minimum balance = Rs. 4500
In the month of April the balance till 11^th will be Rs. 4500 (carried over from the month of March). Then it is increased to Rs. 6730 till the end of the April month. So, the minimum of these two is Rs. 4500. Therefore, at the end of April, the minimum balance = Rs. 6730
As no transaction is done in the month of May so the balance at the end of May will be same as that of April, i.e. Rs. 6730. So, the minimum balance = Rs. 6730
At the end of June, the minimum balance = Rs. 1730
At the end of July, the minimum balance = Rs. 7730
On adding the minimum balance of respective months, i.e.,
4500+4500+4500+6730+1730+7730 = Rs.29690
So the principal amount is Rs. 29,690/-.
Now we have to calculate simple interest (SI) on the principal amount month wise at the rate of 6%.
We are now using the formula,
$SI=\dfrac{Principle\times Rate\times Time}{100}$
Here principle is Rs29690, rate is 6% and time is 1 month or $\left( \dfrac{1}{12} \right)$ years.
So,
$SI=\dfrac{29690\times 6\times \dfrac{1}{12}}{100}=148.95$
Therefore, the interest earned is Rs.148.95/-.

Note: In banking type of problems, if the students make mistakes in filling up the table, the entire problem may be wrong.
Another mistake possible in this case is while calculating the minimum balance in case of March and May. They may forget to add these months' balance.